The prior are includes self-balancing, single wheel structure vehicles. One example is the Solowheel, described in U.S. Pat. No. 8,807,250 issued to Chen (the inventor herein) on Aug. 19, 2014, and entitled Powered Single-Wheel Self-Balancing Vehicle for Standing User. Another example is the device of Simeray, described in U.S. Pat. No. 8,616,313, issued on Dec. 31, 2013, and entitled Motorized Transport Vehicle for a Pedestrian.
These prior art devices illustrate the use of drive motors and related components that may be disadvantageously heavy, power consumptive (requiring more and heavier batteries) and/or bulky.
With respect to overall device weight, it is desirable to have a lightweight device. This would permit a user to readily stow or carry the device. Consider, for example, a user who might use the device to get to a bus stop, stow the device during the bus ride and then remount the device upon descending the bus. This on-again, off-again stow and unstow routine could be repeated for other errands or destinations through the day. It is desirable in this instance that the device is sufficiently lightweight to be readily carried or stowed, for example, in a backpack or the like.
With respect to drive systems, small, lightweight and higher efficiency friction drive motors are known in the art. One embodiment of a friction drive motor is shown in FIG. 3 herein and others are shown in U.S. patent application Ser. No. 14/811,702, filed Jul. 28, 2015, by Chen, and entitled Fore-Aft Self-Balancing Transportation Device with Low and Centered Foot Platform, which is hereby incorporated by reference as though disclosed in its entirety herein. These devices include the positioning of a drive head onto the interior surface of the rim. When it is raining or other moisture is present, however, the contact surface of the rim may become wet causing the drive head to “slip” on the rim contact surface, thereby reducing the ability of the device to perform fore-aft self-balancing and diminishing user control of the device.
Thus, a need exists to inhibit moisture penetration into the wheel envelope or onto the drive head or drive surface of a personal transportation device so that lightweight and more energy efficient friction drive motors may be used in these devices.